U.S. patent application number 17/431284 was filed with the patent office on 2022-05-05 for manufacturing method of nitrile compound.
This patent application is currently assigned to Mitsubishi Gas Chemical Company, Inc.. The applicant listed for this patent is Mitsubishi Gas Chemical Company, Inc.. Invention is credited to Masayoshi UENO.
Application Number | 20220135515 17/431284 |
Document ID | / |
Family ID | 1000006106436 |
Filed Date | 2022-05-05 |
United States Patent
Application |
20220135515 |
Kind Code |
A1 |
UENO; Masayoshi |
May 5, 2022 |
MANUFACTURING METHOD OF NITRILE COMPOUND
Abstract
A manufacturing method of a nitrile compound comprising a first
step of introducing a raw material gas containing a cyclic compound
having an organic substituent, ammonia, and air into a reactor and
reacting the raw material gas in the presence of a catalyst to
generate the nitrile compound, a second step of discharging a
reacted gas from the reactor and separating the nitrile compound
from the reacted gas, and a third step of collecting mist from a
first residual gas obtained by separating the nitrile compound from
the reacted gas to remove water and ammonium carbonate in the first
residual gas.
Inventors: |
UENO; Masayoshi;
(Niigata-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Mitsubishi Gas Chemical Company, Inc. |
Chiyoda-ku |
|
JP |
|
|
Assignee: |
Mitsubishi Gas Chemical Company,
Inc.
Chiyoda-ku
JP
|
Family ID: |
1000006106436 |
Appl. No.: |
17/431284 |
Filed: |
March 25, 2020 |
PCT Filed: |
March 25, 2020 |
PCT NO: |
PCT/JP2020/013435 |
371 Date: |
August 16, 2021 |
Current U.S.
Class: |
558/327 |
Current CPC
Class: |
C07C 253/28
20130101 |
International
Class: |
C07C 253/28 20060101
C07C253/28 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 29, 2019 |
JP |
2019-065750 |
Claims
1. A method of manufacturing a nitrile compound, comprising:
introducing a raw material gas comprising a cyclic compound having
an organic substituent, ammonia, and air into a reactor such that
the raw material gas reacts in a presence of a catalyst and
generates a nitrile compound; discharging a reacted gas from the
reactor; separating the nitrile compound from the reacted gas such
that a first residual gas is obtained; and collecting mist from the
first residual gas such that water and ammonium carbonate are
removed from the first residual gas.
2. The method of claim 1, wherein the collecting of the mist is
conducted by a mist eliminator.
3. The method of claim 2, wherein the mist eliminator is a
Vane-type mist eliminator.
4. The method of claim 1, wherein the cyclic compound is a
carbocyclic compound or a heterocyclic compound.
5. The method of claim 1, wherein the nitrile compound is an
aromatic nitrile compound.
6. The method of claim 1, wherein the cyclic compound is
meta-xylene, and the nitrile compound is isophthalonitrile.
7. The method of claim 1, further comprising: resupplying to the
reactor a second residual gas obtained by the removing gf the water
and the ammonium carbonate from the first residual gas.
8. The method of claim 7, wherein the resupplying includes
supplying the second residual gas in an amount of 10 to 60 vol %
based on the raw material gas freshly supplied through an inlet of
the reactor.
9. The method of claim 2, wherein the cyclic compound is a
carbocyclic compound or a heterocyclic compound.
10. The method of claim 3, wherein the cyclic compound is a
carbocyclic compound or a heterocyclic compound.
11. The method of claim 2, wherein the nitrile compound is an
aromatic nitrile compound.
12. The method of claim 4, wherein the nitrile compound is an
aromatic nitrile compound.
13. The method of claim 2, wherein the cyclic compound is
meta-xylene, and the nitrile compound is isophthalonitrile.
14. The method of claim 4, wherein the cyclic compound is
meta-xylene, and the nitrile compound is isophthalonitrile.
15. The method of claim 5, wherein the cyclic compound is
meta-xylene, and the nitrile compound is isophthalonitrile.
16. The method of claim 2, further comprising: resupplying to the
reactor a second residual gas obtained by the removing of the water
and the ammonium carbonate from the first residual gas.
17. The method of claim 3, further comprising: resupplying to the
reactor a second residual gas obtained by the removing of the water
and the ammonium carbonate from the first residual gas.
18. The method of claim 4, further comprising: resupplying to the
reactor a second residual gas obtained by the removing of the water
and the ammonium carbonate from the first residual gas.
19. The method of claim 5, further comprising: resupplying to the
reactor a second residual gas obtained by the removing of the water
and the ammonium carbonate from the first residual gas.
20. The method of claim 6, further comprising: resupplying to the
reactor a second residual gas obtained by the removing of the water
and the ammonium carbonate from the first residual gas.
Description
TECHNICAL FIELD
[0001] The present invention relates to a manufacturing method of a
nitrile compound such as a carbocyclic nitrile compound or a
heterocyclic nitrile compound by ammoxidation reaction using a
cyclic compound such as a carbocyclic compound or a heterocyclic
compound having an organic substituent as a raw material.
BACKGROUND ART
[0002] A carbocyclic nitrile compound is useful as a raw material
for manufacturing of a synthetic resin, an agricultural chemical,
etc. and an intermediate raw material of an amine, an isocyanate,
etc. On the other hand, a heterocyclic nitrile compound is useful
as an intermediate raw material of a medicament, a feed additive, a
food additive, etc. A method of reacting an organic compound such
as a carbocyclic compound or a heterocyclic compound (hereinafter
sometimes referred to as a "cyclic compound") having an organic
substituent with ammonia and an oxygen-containing gas is referred
to as "ammoxidation", and generally a nitrile compound is
manufactured by gas phase catalytic reaction. As a catalyst used
for ammoxidation, a catalyst containing vanadium, molybdenum, iron,
etc. is known.
[0003] In ammoxidation, a nitrile compound which is the objective
substance is separated from a reacted gas and recovered; however,
the residual gas after separating a nitrile compound comprises
water, nitrogen, oxygen, ammonia, carbon dioxide, carbon monoxide,
an unreacted carbocyclic compound or heterocyclic compound, etc.
(for example, see Patent Literatures 1 and 2 below).
CITATION LIST
Patent Literature
[0004] Patent Literature 1: Japanese Patent Laid-Open No.
2003-238511 [0005] Patent Literature 2: Japanese Patent Laid-Open
No. 54-16445
SUMMARY OF INVENTION
Technical Problem
[0006] It is generally known that, In the condition in which carbon
dioxide and ammonia exist, ammonium carbonate is generated which is
solid at room temperature. There is a concern about clogging of the
line due to deposition of ammonium carbonate in a place where the
temperature is lower than or equal to the melting point of ammonium
carbonate.
[0007] In ammoxidation reaction, reaction conditions such as
composition of a feed gas, contact time, and reaction temperature
are important factors which determine the yield of the nitrile
compound and productivity, and are generally controlled strictly.
However, when a nitrile compound is manufactured by ammoxidation,
air is used as an oxygen source in industrial manufacturing, but
the oxygen concentration in the air is not constant in the case of
using air as an oxygen source.
[0008] Therefore, as a method of maintaining the oxygen
concentration at a constant level without adding a facility for
supplying pure oxygen gas, Patent Literature 1 proposes a method in
which a residual gas obtained by separating the nitrile compound
from a reacted gas is resupplied to a reactor in the proportion of
10 to 60 vol % based on a raw material gas freshly supplied to the
reactor and comprising the carbocyclic compound or heterocyclic
compound, ammonia, and air. However, in the above method, the
residual gas obtained by separating the nitrile compound from the
reacted gas is returned to the reactor for the purpose of
maintaining the oxygen concentration at a constant level, and thus
when ammonium carbonate in the residual gas deposits and clogs the
line, the amount of the residual gas supplied is difficult to
control, and maintaining the target oxygen concentration at a
constant level may be difficult.
[0009] On the other hand, there was a concern about increase in
size of the facility when a cooling apparatus, etc. are
additionally installed for recovering the ammonium carbonate.
Furthermore, installation of a large-size cooling apparatus having
high performance causes a problem in cost as well.
[0010] The object of the present invention is to provide a
manufacturing method of a nitrile compound which enables
suppression of deposition of ammonium carbonate and stable
manufacturing of a nitrile compound, in order to solve the above
problems.
Solution to Problem
[0011] The present inventors engaged in diligent study and
consequently achieved the present invention by discovering that in
the method of synthesizing a nitrile compound such as a carbocyclic
nitrile compound or a heterocyclic nitrile compound by ammoxidation
reaction using a cyclic compound such as a carbocyclic compound or
a heterocyclic compound having an organic substituent as a raw
material, ammonium carbonate contained in a residual gas together
with water can be removed by collecting mist from the residual gas
without attempting increase in size of a facility.
[0012] <1> A manufacturing method of a nitrile compound
comprising
[0013] a first step of introducing a raw material gas containing a
cyclic compound having an organic substituent, ammonia, and air
into a reactor and reacting the raw material gas in the presence of
a catalyst to generate the nitrile compound,
[0014] a second step of discharging a reacted gas from the reactor
and separating the nitrile compound form the reacted gas, and
[0015] a third step of collecting mist from a first residual gas
obtained by separating the nitrile compound from the reacted gas to
remove water and ammonium carbonate in the first residual gas.
[0016] <2> The manufacturing method of a nitrile compound
according to the above <1>, wherein the mist is removed from
the first residual gas by a mist eliminator in the third step.
[0017] <3> The manufacturing method of a nitrile compound
according to the above <2>, wherein the mist eliminator is a
Vane-type mist eliminator.
[0018] <4> The manufacturing method of a nitrile compound
according to any of the above <1> to <3>, wherein the
cyclic compound is a carbocyclic compound or a heterocyclic
compound.
[0019] <5> The manufacturing method of a nitrile compound
according to any of the above <1> to <4>, wherein the
nitrile compound is an aromatic nitrile compound.
[0020] <6> The manufacturing method of a nitrile compound
according to any of the above <1> to <5>, wherein the
cyclic compound is meta-xylene, and the nitrile compound is
isophthalonitrile.
[0021] <7> The manufacturing method of a nitrile compound
according to any of the above <1> to <6>, wherein a
second residual gas obtained by removing the water and the ammonium
carbonate from the first residual gas is resupplied to the
reactor.
[0022] <8> The manufacturing method of a nitrile compound
according to the above <7>, wherein an amount of the second
residual gas supplied to the reactor is 10 to 60 vol % based on the
raw material gas freshly supplied through an inlet of the
reactor.
Advantageous Effect of Invention
[0023] According to the present invention, a manufacturing method
of a nitrile compound which enables suppression of deposition of
ammonium carbonate and stable manufacturing of a nitrile compound
can be provided.
BRIEF DESCRIPTION OF DRAWINGS
[0024] FIG. 1 is a schematic view showing an example of the
manufacturing process of a nitrile compound of the present
embodiment.
[0025] FIG. 2 is a schematic view showing the structure of the
reactor of the present embodiment.
DESCRIPTION OF EMBODIMENTS
[0026] Hereinafter, the present invention will be described in
detail, but the present invention is not limited to each embodiment
shown below.
<Manufacturing Method of Nitrile Compound>
[0027] The manufacturing method of a nitrile compound of the
present embodiment (hereinafter sometimes simply referred to as
"the manufacturing method of the present embodiment") comprises
[0028] a first step of introducing a raw material gas containing a
cyclic compound having an organic substituent, ammonia, and air
into a reactor and reacting the raw material gas in the presence of
a catalyst to generate a nitrile compound,
[0029] a second step of discharging a reacted gas from the reactor
and separating the nitrile compound form the reacted gas,
[0030] a third step of collecting mist from a first residual gas
obtained by separating the nitrile compound from the reacted gas to
remove water and ammonium carbonate in the first residual gas.
[0031] According to the manufacturing method of the present
embodiment, in the third step, ammonium carbonate dissolved in
water in the mist can be removed from the first residual gas by
collecting the mist in the gas from the first residual gas using a
mist eliminator, etc. Thus, since ammonium carbonate in the
residual gas which is to be resupplied to the reactor can be
removed, clogging of the line due to deposition of ammonium
carbonate can be prevented in the resupply line of the residual
gas. Therefore, according to the manufacturing method of the
present embodiment, it is possible to maintain the oxygen
concentration in the gas supplied to the reactor at a constant
level and to stably manufacture the nitrile compound.
[First Step]
[0032] The first step is a step of introducing a raw material gas
containing a cyclic compound having an organic substituent,
ammonia, and air into a reactor and reacting the raw material gas
in the presence of a catalyst to generate a nitrile compound. In
the present embodiment, a "raw material gas" refers to a gas
supplied to a reactor, and contains at least a cyclic compound
having an organic substituent, ammonia, and air. In the first step,
for example, a nitrile compound such as an aromatic nitrile
compound is generated by ammoxidation reaction using the raw
material gas. The reacted gas containing the nitrile compound
generated in the reactor is discharged from the reactor in the
second step.
(Cyclic Compound Having an Organic Substituent)
[0033] Examples of the cyclic compound having an organic
substituent used in the raw material gas of the present embodiment
include a carbocyclic compound or a heterocyclic compound having an
organic substituent. Hereinafter, a cyclic compound having an
organic substituent may be referred to as a "cyclic compound of the
present embodiment".
[0034] The carbocyclic compound having an organic substituent is a
carbocyclic compound having a carbocyclic ring such as benzene,
naphthalene, anthracene, cyclohexene, cyclohexane,
dihydronaphthalene, tetralin, and decalin, and having, as a side
chain, an organic substituent, such as a methyl group, an ethyl
group, a propyl group, a formyl group, an acetyl group, a
hydroxymethyl group, and a methoxycarbonyl group. The carbocyclic
compound may further comprise a substituent which does not
participate in ammoxidation reaction such as a halogen group, a
hydroxyl group, an alkoxy group, a phenyl group, an amino group,
and a nitro group.
[0035] Specific examples of the carbocyclic compound having an
organic substituent include toluene, xylene, trimethylbenzene,
ethylbenzene, methylnaphthalene, dimethylnaphthalene,
methyltetralin, dimethyltetralin, chlorotoluene, dichlorotoluene,
methylaniline, cresol, and methyl anisole.
[0036] The heterocyclic compound having an organic substituent is a
heterocyclic compound having the above organic substituent on a
heterocyclic ring such as furan, pyrrole, indole, thiophene,
pirazole, imidazole, oxazole, pyrane, pyridine, chinoline,
isochinoline, pyrroline, pyrrolidine, imidazoline, imidazolidine,
piperidine, and piperazine. Furthermore, similarly to the above
carbocyclic compound, the heterocyclic compound may have a
substituent not participating in ammoxidation reaction as a side
chain.
[0037] Specific examples of a heterocyclic compound having an
organic substituent include furfural, 2-methylthiophene,
3-methylthiophene, 2-formylthiophene, 4-methylthiazol,
methylpyridine, dimethylpyridine, trimethylpyridine,
methylchinolin, methylpyrazine, dimethylpyrazine, and
methylpiperazine. These compounds may be used alone or in the form
of a mixture.
[0038] The manufacturing method of the present embodiment is
particularly preferably applied to a method in which meta-xylene
having two methyl groups on a benzene ring is used as the above
cyclic compound and isophthalonitrile which is an aromatic nitrile
compound is manufactured as a nitrile compound generated using the
cyclic compound.
[0039] The concentration of the cyclic compound of the present
embodiment in the raw material gas of the present embodiment is
preferably 0.2 to 10 vol %, more preferably 0.5 to 5 vol % from the
viewpoint of the yield and space time yield of the nitrile
compound. When the present embodiment is implemented, the
concentration of the cyclic compound of the present embodiment is
preferably 0.07 moles or less as the number of moles of the organic
substituent based on 1 mole of all components supplied to the
reactor. The number of moles of the organic substituent based on 1
mole of all components supplied to the reactor represents a value
obtained by multiplying the concentration by volume of the compound
having an organic substituent and the number of the organic
substituent contained in the compound having an organic
substituent. For example, 1.5 vol % of xylene (having two methyl
groups as organic substituents) gives an organic substituent
concentration of 0.015.times.2=0.03 moles based on 1 mole of all
components supplied to the reactor.
[0040] "vol %" in the present embodiment means a ratio of volume
under so-called standard conditions at 0.degree. C. and 1 atm.
(Catalyst)
[0041] As described above, in the manufacturing method of the
present embodiment, a raw material gas is supplied in the presence
of a catalyst and a nitrile compound is manufactured by gas phase
catalytic ammoxidation reaction. Examples of a reaction system of
ammoxidation reaction include reaction systems such as a fixed bed,
moving bed, and fluidized bed, but a fluidized bed system is
preferably used from the viewpoint of control of the reaction
temperature, the cost of an apparatus, etc. The catalyst used in
the present embodiment is not particularly limited as long as it is
an ammoxidation catalyst suitable for gas phase catalytic reaction.
As the catalyst, for example, a catalyst containing an oxide of at
least one element selected from vanadium, molybdenum, and iron is
preferably used. In the case of a fluidized bed catalyst used for a
fluidized bed system, the particle size of the catalyst is
preferably within the range of 10 to 300 .mu.m, and the average
particle size is within the range of 30 to 200 .mu.m, preferably 40
to 100 .mu.m. The bulk density of the catalyst is preferably within
the range of 0.5 to 2 g/cm.sup.3, preferably 0.7 to 1.5
g/cm.sup.3.
(Ammonia)
[0042] Ammonia contained in the raw material gas of the present
embodiment is not particularly limited, but industrial grade
ammonia can be used. When the amount of ammonia to be used is too
small, the yield of the nitrile compound reduces; on the other
hand, when the amount of ammonia to be used is too large, an
industrial disadvantage results from loss of unreacted ammonia or
increase in cost of recovery. From such a viewpoint, the amount of
ammonia to be used is preferably within such range that the molar
ratio of ammonia to the organic substituents contained in the
cyclic compound of the present embodiment in the raw material gas
(NH.sub.3/organic substituent) is 1 to 10 times by mole, preferably
3 to 7 times by mole.
[0043] In the present embodiment, the configuration may be provided
wherein a nitrile compound which is the objective substance is
separated from the reacted gas discharged through a reactor outlet,
then mist in the residual gas component (the first residual gas)
after separation is removed to obtain the second residual gas,
which is then resupplied to the ammoxidation reactor. When ammonia
is contained in the first and second residual gas in a
non-negligible amount, the amount of freshly supplied ammonia may
be appropriately adjusted.
(Air)
[0044] In the manufacturing method of the present embodiment, air
is used as an oxygen source. When the amount of air to be used is
too small, the yield of the nitrile compound reduces, and when the
amount is too large, the space time yield reduces. From such a
viewpoint, the amount of air to be used is preferably adjusted so
that the molar ratio of oxygen to the organic substituents
contained in the cyclic compound of the present embodiment in the
raw material gas (O.sub.2/organic substituent) is within the range
of 1.5 to 7 times by mole, preferably 1.5 to 5 times by mole.
(Ammoxidation Reaction)
[0045] The reaction pressure of ammoxidation conducted in a reactor
in the presence of a catalyst may be normal pressure, increased
pressure, or reduced pressure, but is preferably within the range
from around normal pressure to 0.2 MPa. The contact time of the raw
material gas with the catalyst depends on conditions such as the
type of the cyclic compound of the present embodiment, the
composition of the supplied raw material, and the reaction
temperature, but is usually within the range of 0.5 seconds to 30
seconds.
[0046] In the reaction of the raw material gas in the presence of a
catalyst in the reactor, when the reaction temperature is low, a
sufficient reaction rate cannot be obtained. On the other hand,
when the reaction temperature is too high, production of byproducts
such as carbon dioxide and hydrogen cyanide increases and the yield
of the nitrile compound reduces. From such a viewpoint, the above
reaction temperature is usually about 300 to 500.degree. C.,
preferably within the range of 330 to 470.degree. C. Preferably,
the above reaction temperature is appropriately selected as a
temperature which provides an optimum yield, while considering the
activity of the catalyst, etc. under the above operating
condition.
[Second Step]
[0047] The second step is a step of discharging a reacted gas from
the reactor and separating the nitrile compound form the reacted
gas. "Reacted gas" in the present embodiment means a gas containing
at least a nitrile compound generated in the reactor. Furthermore,
the reacted gas containing the nitrile compound generated in the
reactor in the first step contains "residual gas components" such
as ammonia, hydrogen cyanide, carbon dioxide, water, carbon
monoxide, nitrogen, oxygen, and a cyclic compound such as an
unreacted carbocyclic compound or a heterocyclic compound in
addition to the nitrile compound.
[0048] The second step is, for example, conducted in a nitrile
collection column, etc. described below. The gas obtained by
separating the nitrile gas in the second step is transferred as the
first residual gas to the third step which is the next step.
(Separation of Nitrile Compound)
[0049] Examples of a method of separating and collecting a nitrile
compound from a reacted gas include a method (1) in which a reacted
gas is contacted with an organic solvent which can dissolve a
nitrile compound and the nitrile compound is collected in the
solvent to be separated from the residual gas component, and a
method (2) in which a reacted gas is cooled and a nitrile compound
is deposited as a solid or condensed as a liquid to be separated
from the residual gas component.
[0050] In the case of the above method (1), an organic solvent such
as an alkylbenzene, a heterocyclic compound, an aromatic nitrile,
and a heterocyclic nitrile is used as an organic solvent. Using the
nitrile compound generated in ammoxidation reaction as the organic
solvent is advantageous because the kinds of substances to be
handled do not increase. In the manufacturing method of the present
embodiment, for example, when isophthalonitrile is obtained using
meta-xylene as a cyclic compound of the present embodiment,
metatolunitrile generated as a byproduct in ammoxidation reaction
can be preferably used as a catalyst.
[Third Step]
[0051] The third step is a step of collecting mist from a first
residual gas obtained by separating the nitrile compound from the
reacted gas to remove water and ammonium carbonate in the first
residual gas. In the present embodiment, "first residual gas" means
a gas containing the above residual gas components and obtained by
separating the nitrile compound from the reacted gas. However, the
first residual gas may contain the nitrile compound which has not
been separated in the second step.
[0052] The first residual gas contains nitrogen as a main
component, and in addition, contains ammonia, hydrogen cyanide,
carbon dioxide, water, carbon monoxide, oxygen, cyclic compounds
such as an unreacted carbocyclic compound or a heterocyclic
compound, and the like, which are the above residual gas
components. The temperature of the first residual gas containing
carbon dioxide and ammonia and obtained by separating the nitrile
compound is generally lower than that of the reacted gas, and in a
temperature lower than or equal to the thermal decomposition
temperature of ammonium carbonate, ammonium carbonate having high
solubility in water is likely to generate. Ammonium carbonate in
the first residual gas is usually contained in the first residual
gas in the state of being dissolved in mist-form water.
[0053] Furthermore, in the manufacturing method of the present
embodiment, for example, a step of contacting the first residual
gas with water and collecting ammonia and hydrogen cyanide
contained in the first residual gas may be provided after the
second step and before the third step.
[0054] In the third step, mist is collected from the first residual
gas. In the present embodiment, "mist" means liquid particles and
is not particularly limited, but it is usually formed by
condensation of steam, spraying of liquid, or the like, and it
means liquid particles having a particle size of 0.01 .mu.m to
several tens of m. In the third step, water existing as mist in the
first residual gas is collected, and thus ammonium carbonate
dissolved in the water can be removed along with water. In addition
to ammonium carbonate, the mist may contain carbon dioxide and
ammonia which are components constituting ammonium carbonate. The
first residual gas usually contains water as mist due to
entrainment phenomenon, but the amount of mist in the first
residual gas may be controlled by adjusting pressure and
temperature in the reactor, etc.
[0055] On the other hand, for example, when isophthalonitrile is
manufactured using xylene, a large amount of water is generated by
the reaction. The water generated by the reaction is likely to be
in the form of mist when the gas flow rate is high. Since water in
the mist form is likely to be entrained by a circulating gas, it is
difficult to be discharged to the outside of the reaction system
compared to the case of a water droplet which has a large size to
some extent, and thus it is likely to be retained in the reaction
system. On the other hand, in the manufacturing method of the
present embodiment, the mist is directly collected in the third
step, and thus the amount of the mist existing in the reaction
system can be reduced, and an effect of suppressing deposition of
ammonium carbonate can be more enhanced.
[0056] In the third step, "collecting mist" differs from means for
recovering mist as comparatively large liquid particles such as
water droplets by controlling the temperature and pressure of the
first residual gas, for example, a cooling apparatus, and it means
collecting mist by a mechanism such as inertial collision against a
collector, diffusion, shielding, and gravity. As means for
collecting mist from the first residual gas, for example, a mist
eliminator can be used.
(Mist Eliminator)
[0057] A "mist eliminator" is also referred to as a mist separator,
and is an apparatus having a mist collecting mechanism which
utilizes inertial collision against a collector, diffusion,
shielding, gravity, etc. Examples of the mist eliminators include a
mesh type, Vane-type, and candle-type mist eliminators, and a
commonly known mist eliminator can be used. These mist eliminators
can be also classified depending on the collecting method to be
used (for example, inertial collision against a collector,
diffusion due to Brownian motion of mist, and gravity). For
example, a mesh-type and Vane-type mist eliminator utilizes
inertial collision against a collector, and a candle-type mist
eliminator utilizes Brownian motion. As the mist eliminator, a
known mist eliminator can be appropriately selected and used, and
when a mist eliminator is used for industrial manufacturing of a
nitrile compound, a Vane-type mist eliminator can be preferably
used which can be adapted to a large gas flow rate. A Vane-type
mist eliminator is a mist eliminator utilizing inertial collision
against a collector, and can be preferably used under the condition
in which high load and high flow rate are required. The principle
of a mist eliminator (separator) and other details are described
in, for example, "Mist separator no seino to sono ouyou (in
Japanese) (Performance of mist separator and application thereof)"
K. Okuyama (Kankyo Gijyutsu (in Japanese) (Environmental
Engineering), 2 (11), pp. 824-830, 1973).
[Other Steps]
[0058] The manufacturing method of the present embodiment may
comprise a step of resupplying the second residual gas to the above
reactor, the second residual gas being obtained by removing the
water and the ammonium carbonate from the first residual gas in the
third step. In the present embodiment, "the second residual gas"
means the first residual gas from which mist has been collected in
the third step. The second residual gas contains at least oxygen,
and in addition, contains carbon dioxide, carbon monoxide,
nitrogen, oxygen, a cyclic compound such as an unreacted
carbocyclic compound or heterocyclic compound, etc. Furthermore,
the second residual gas may contain the nitrile compound and water
which have not been removed in the second and the third step.
[0059] When the second residual gas is resupplied to the reactor,
the amount of the second residual gas supplied to the reactor is
preferably 10 to 60 vol %, more preferably 15 to 50 vol % based on
the amount of the raw material gas freshly supplied through the
reactor inlet from the viewpoint of an effect of stabilizing the
oxygen concentration in the supplied gas, the circulating amount,
and the space time yield.
[0060] In the present embodiment, the second residual gas is
resupplied to the reactor.
[Flow of Manufacturing Method of the Present Embodiment]
[0061] Hereinafter, the flow of the manufacturing method of the
present embodiment will be described with reference to FIG. 1. FIG.
1 is a schematic view showing an example of the manufacturing
process of a nitrile compound of the present embodiment.
[0062] In the manufacturing method of the present embodiment shown
in FIG. 1, ammoxidation reaction is conducted by fluidized bed
reaction, the reacted gas discharged from the reactor is contacted
with a solvent to conduct collecting, and the first residual gas
after collecting is further contacted with water to collect
ammonia. After that, mist is removed from the first residual gas by
a mist eliminator, then the second residual gas is resupplied to
the ammoxidation reactor.
[0063] In FIG. 1, the manufacturing apparatus used for the
manufacturing method of the present embodiment comprises an
ammoxidation reactor 1, a nitrile collection column 2, a water
washing column 3, and a mist eliminator 4. A fluidized bed catalyst
is filled in the ammoxidation reactor 1. A raw material gas
containing the cyclic compound of the present embodiment, ammonia,
and air, and the residual gas for resupplying (the second residual
gas) are supplied to the ammoxidation reactor 1 to conduct
ammoxidation reaction. A cooling pipe is provided inside the
reactor, and the fluidized bed catalyst is provided so that the
interface of the fluidized bed catalyst layer is under the upper
end of the cooling pipe. After catalyst particles are separated
from the raw material gas using a catalyst cyclone, which is not
shown, and the raw material gas is returned to the fluidized bed
catalyst layer via a return pipe, the raw material gas is
discharged as the reacted gas through a discharging pipe. The
reacted gas discharged from the ammoxidation reactor 1 contains a
nitrile compound, ammonia, hydrogen cyanide, carbon dioxide, water,
carbon monoxide, nitrogen, oxygen, an unreacted cyclic compound of
the present embodiment, etc., and is transferred to the nitrile
collection column 2 of the next step. In the nitrile collection
column 2, the reacted gas is contacted with a solvent to collect
the nitrile compound contained in the reacted gas, and thus the
nitrile compound is separated from the reacted gas. The first
residual gas after collecting the nitrile is transferred to the
water washing column 3 of the next step. In the water washing
column 3, the residual gas is contacted with water to collect
ammonia and hydrogen cyanide contained in the first residual gas.
Then, the first residual gas is supplied to the mist eliminator,
and mist in the gas is collected to remove water and ammonium
carbonate from the first residual gas. The second residual gas
discharged from the mist eliminator is resupplied to the
ammoxidation reactor 1 as a gas for resupplying. The apparatus may
be configured so that a part of the second residual gas is supplied
to the ammoxidation reactor 1, and the rest of the second residual
gas is transferred to a waste gas treatment facility such as an
incinerator.
[0064] Hereinabove, the present invention has been described with
reference to the embodiments, but these embodiments are examples
and do not limit the present invention.
EXAMPLES
[0065] Hereinafter, the present invention will be described more
specifically with reference to Examples. However, the present
invention is not limited to these Examples. The result of the
reaction in the Examples below is a ratio based on meta-xylene as a
raw material.
Example 1
[0066] <Preparation of Catalyst>
[0067] An aqueous solution of chromic acid was prepared by
dissolving 196 g of chromic anhydride CrO.sub.3 in 200 mL of pure
water.
[0068] Then, an aqueous solution of oxalic acid was prepared by
adding 600 mL of pure water to 753 g of oxalic acid and heating the
obtained mixture to 50.degree. C. to 60.degree. C. To this aqueous
solution of oxalic acid with stiring, the aqueous solution of
chromic acid was gradually added to prepare an aqueous solution of
chromium oxalate.
[0069] Then, after dissolving 444 g of oxalic acid in 400 mL of
pure water and heating the obtained mixture to 80 to 90.degree. C.,
178 g of vanadium pentoxide V.sub.2O.sub.5 was gradually added to
the mixture while sufficiently stirring to prepare an aqueous
solution of vanadyl oxalate. Furthermore, the aqueous solution of
chromium oxalate prepared as described above was added dropwise to
and mixed with the aqueous solution of vanadyl oxalate prepared as
described above at 70.degree. C. to 90.degree. C. 12.1 g of boric
acid was added to and mixed with this mixed aqueous solution at
70.degree. C. to 90.degree. C. The thus prepared catalyst solution
was heated to 85.degree. C. to 95.degree. C. and subjected to
aging. Then, the solution was concentrated at 100.degree. C. to
110.degree. C. 1333 g of titanium oxide of anatase-type was added
to the concentrated liquid formulation, and the formulation was
kneaded using a kneader at 70.degree. C. until it became uniform
while water was evaporated. Then, the obtained cake was dried by a
dryer at 110.degree. C.
[0070] Then, the dried product was pre-baked in a baking furnace at
400.degree. C. for 2 hours, then pulverized by a pulverizer. 4% by
mass of Graphite was added to and mixed with the pulverized powder.
Then this raw material powder was formed into a tablet using a
tablet molding machine so that a ring-shaped tablet having outer
diameter of 5.7 mm, inner diameter of 2.4 mm, and height of 5.8 mm
was obtained. After molding, the tablet was baked in a baking
furnace at 600.degree. C. for 15 hours. The atomic ratio of this
catalyst was Cr:V:B=1.0:1.0:0.1, and the concentration of titania
support in the catalyst was 80% by mass.
<Manufacturing of Nitrile Compound>
[0071] As shown in FIG. 2, downward flow part of the inlet side 11
of the reaction tube 10 was a preheating layer, upward flow part of
the outlet side 12 of the reaction tube 10 was a catalyst layer.
Then, the catalyst obtained as described above was fractured into 8
pieces using pliers, then sieved with a 1.25 mm mesh, and
subsequently sieved with a 0.95 mm mesh to prepare the fractured
catalyst A having a size of 0.95 to 1.25 mm. 10 g of fractured
catalyst A was filled over the whole catalyst layer.
[0072] A reaction tube was installed in a fused salt bath
maintained at 400.degree. C., an inlet side tube and an outlet side
tube of the reaction tube were heated and heat-retained by a
heater. As raw materials, 1.95 g/hr of meta-xylene, 2.45 g/hr of
ammonia, 155 Nml/min of air, and 390 Nml/min of nitrogen were
introduced into the reaction tube at normal pressure and subjected
to catalytic reaction. The reacted gas was absorbed by
tetrahydrofuran, and "GC-2010" gas chromatograph manufactured by
SHIMADZU CORPORATION and a column "DB-1" (length 60 m, thickness
0.25 micrometer, inner diameter 0.25 mm (manufactured by Agilent
Technologies, Inc.)) were used with tridecane as an internal
standard, and a column temperature of 120.degree. C. was retained
for 5 minutes under the conditions of 15 ml/min of helium carrier,
an inlet temperature of 235.degree. C., a split ratio of 11,
detector FID, 235.degree. C. After that, the column temperature was
increased by 40.degree. C./min up to 230.degree. C. and retained
for 10 minutes, and analysis was conducted under the condition of 1
microliter of injection volume. As results of analysis, the
conversion ratio of meta-xylene was 90%, the yield of
isophthalonitrile was 60%.
[0073] Then, isophthalonitrile was absorbed by passing the reacted
gas through 30 ml of m-tolunitrile.
[0074] Furthermore, water was removed from the gas after removing
isophthalonitrile (the first residual gas) using a mist separator
having filtration rating of 40 .mu.m (product name, BN-2720-8
manufactured by NIPPON SEIKI CO., LTD.).
[0075] After that, the obtained gas (the second residual gas) was
passed through 50 cm Teflon.RTM. tube having an inner diameter of 6
mm.
[0076] After conducting reaction for 15 minutes, as a result of
checking the Teflon tube, white powder was adhered to the tube. The
tube was washed with 30 ml of water, and the white powder was
recovered. The washing water used for recovery was subjected to
titration with 0.1 mol/L aqueous solution of hydrochloric acid
using neutralization titration apparatus "COM-1700" manufactured by
HIRANUMA SANGYO Co., Ltd.
[0077] As a result, the initial pH was 9, and a curve having two
stages was obtained. As a result of checking the amount of
recovered ammonium carbonate using the peak of the second stage,
0.004 mol of ammonium carbonate was confirmed.
Comparative Example 1
[0078] Isophthalonitrile was produced similarly to Example 1 except
that a mist separator was not used. The content of ammonium
carbonate was measured for the finally obtained gas similarly to
Example 1.
[0079] The amount of ammonium carbonate recovered from Teflon tube
was 0.01 mol.
[0080] Unlike the Example, a large amount of white powder was
adhered to the Teflon tube, and there was a concern about
clogging.
[0081] The disclosure of Japanese Patent Application No.
2019-065750 filed on Mar. 29, 2019 is herein incorporated by
reference in its entirety.
[0082] All literatures, patent applications, and engineering
standards described in the specification are incorporated herein by
reference to the same extent as the case in which it is shown
specifically and individually that individual literature, patent
application, and engineering standard are incorporated by
reference.
REFERENCE SIGNS LIST
[0083] 1 ammoxidation reactor [0084] 2 nitrile collection column
[0085] 3 water washing column [0086] 4 mist eliminator [0087] 10
reactor [0088] 11 downward flow part of the inlet side [0089] 12
upward flow part of the outlet side
* * * * *